shrinked single commit of github/wonseok/khypervisor v1->v1_vdev
refactored vdev related changes
removed confusing/unused macro from vdev_sample.h
[v1-dev] support multiple guest and save banked regs, ttbr0/1 and ttbcr

modified vdev codes for supporting multiple guests
modified context codes for initializing/saving/restoring banked registers
modified context codes for initializing/saving/restoring ttbr0/1 and ttbcr registers
Merge pull request #39 from Wonseok/v1-vdev

[wonseok/v1-dev]  vdev framework and a sample virtual device